In the past, a large number of power semiconductor circuit devices have been configured so as to be cooled by being fixed to a heat sink serving as a heat dissipating member via grease or the like. The grease is used to fill unevenness of a contact surface between the power semiconductor circuit device and the heat sink and to reduce contact thermal resistance. However, thermal conductivity of the grease is considerably small as compared to metals; and therefore, in the case of achieving high heat dissipation of the device, the power semiconductor circuit device needs to be fixed to the heat sink without via the grease.
Consequently, in order to integrate a base board of the heat sink and a base board of the power semiconductor circuit device without via grease that is an impediment to achieving high heat dissipation of the power semiconductor circuit device, a heat dissipating fin of the heat sink is bonded by thermocompression to the base board of the power semiconductor circuit device with a high thermal conductivity insulation resin sheet or formed integrally, and electronic components such as power semiconductor elements and wiring members are mounted on the base board of the power semiconductor circuit device; accordingly, high heat dissipation of the power semiconductor circuit device is achieved. (For example, see Patent Document 1.)